Aluminium extrusion cross-sections
An aluminium extrusion is a constant cross-section pushed through a die, so its weight and stiffness are fixed by the profile shape. Below are common structural and framing cross-sections with dimensions, weight per metre and section properties at 2.7 g/cm³ (6063-T5), plus a tool to draw and render any section of your own.
| Designation | W×H mm | A mm² | Weight kg/m | Ix mm⁴ | Sx mm³ |
|---|---|---|---|---|---|
| 40×40 T-Slot | 40×40 | 579.7 | 1.57 / 0.86 | 109828 | 5491 |
| 20×20 T-Slot | 20×20 | 140.2 | 0.38 / 0.20 | 6856 | 686 |
| SHS 100×100×6 | 100×100 | 2256 | 4.29 | 3.34e+6 | 66717 |
| SHS 50×50×5 | 50×50 | 900.0 | 1.71 / 1.40 | 307500 | 12300 |
| RHS 100×50×4 | 50×100 | 1136 | 2.16 | 1.44e+6 | 28825 |
| L 50×50×8 | 50×50 | 736.0 | 1.40 / 1.20 | 165656 | 4790 |
| CHS ⌀50×5 | 50×50 | 706.9 | 1.34 / 1.10 | 181132 | 7245 |
| FLAT 50×6 | 6×50 | 300.0 | 0.57 / 0.45 | 62500 | 2500 |
Weight column: computed (geometry × density) / published catalogue where known. Section properties integrated exactly from geometry; verify before release.
DXF (LWPOLYLINE/CIRCLE) · CSV/XLSX with X,Y columns (blank row = new loop). DWG → export as DXF first.
EL 69,000 MPa · Aluminium extrusion 6063-T5, clear anodized
| Area | A | 579.7 | mm² |
| Mass / metre | m | 1.565(1.052 lb/ft) | kg/m |
| 2nd moment | Ix | 109828 | mm⁴ |
| 2nd moment | Iy | 109828 | mm⁴ |
| Section mod. | Sx | 5491 | mm³ |
| Section mod. | Sy | 5491 | mm³ |
| Gyration | rx | 13.76 | mm |
| Gyration | ry | 13.76 | mm |
| Torsion | J | — | mm⁴ |
| Published catalogue weight: 0.86 kg/m · computed Δ 82% | |||
Derived exactly from the section polygon (Green’s theorem). Fillets excluded (<2% effect). Verify against certified data before release.
Reading an aluminium extrusion cross-section
The cross-section tells you almost everything: overall envelope, wall thickness, T-slots and bores. Because the section is constant, the area sets the weight per metre (about 2.7 g/cm³ for 6063), and the second moment of area sets bending stiffness. A 40×40 T-slot profile is around 0.8–0.9 kg/m; a 20×20 around 0.2 kg/m.
T-slot and structural framing
T-slot (also called V-slot or profile framing) extrusions dominate machine framing and fixtures. The slots trade some section area for enormous assembly flexibility. Dimviz models a representative slotted section so you can visualise and compare envelopes; for a specific brand series use the published die geometry.
Aluminium vs FRP for the same section
Swap the material in the tool and the geometry stays identical while weight and modulus change: aluminium is stiffer (69 GPa) but heavier and conductive; pultruded FRP is lighter, non-conductive and corrosion-proof but less stiff. The section drawing is the same — the datasheet numbers move.
FAQ
How do I find the weight of an aluminium extrusion?+
Multiply the cross-sectional area (mm²) by 0.0027 (kg per mm² per metre for 6063 aluminium). Dimviz computes the area from your section automatically and shows kg/m.
What is a T-slot extrusion?+
A T-slot (profile framing) extrusion is an aluminium section with T-shaped slots on its faces for bolts and connectors — used for machine frames, guards and fixtures. Common series are 20, 30, 40 and 45 mm.
Can I get section properties for an aluminium profile?+
Yes — area, Ix, Iy, Sx, Sy, radii of gyration and torsion are computed from the section geometry regardless of material; only density and modulus differ.